Investigator

David Shao Peng Tan

Associate Professor · National University of Singapore, Dept of Medicine, Yong Loo Lin School of Medicine

DSPDavid Shao Peng T…
Papers(12)
Prompt Engineering fo…Pembrolizumab plus le…Durvalumab versus Phy…Clearer Horizons: The…Controversies in the …Current practices and…Clinical and biologic…Ovarian cancerHow long is long enou…Quantitative imaging …A single-arm phase II…A step towards the am…
Collaborators(10)
Natalie Y.L. NgoiTuan Zea TanYi Wan LimFélix Blanc-DurandSiew Eng LimChel Hun ChoiSilvana Talisa WijayaMichael FriedlanderDiana LimHwee Lin Wee
Institutions(7)
Duke Nus Medical Scho…National University C…Cancer Science Instit…Institut Gustave Rous…Samsung Medical CenterPrince of Wales Hospi…National University H…

Papers

Prompt Engineering for Eastern Cooperative Oncology Group Status Extraction: Comparing Large Language Model Techniques

PURPOSE Eastern Cooperative Oncology Group (ECOG) performance status is critical for cancer patient management, yet it is often documented only in unstructured clinical notes. This study compares several approaches to extract ECOG status from oncology notes, focusing on advanced prompting techniques for large language models (LLMs). METHODS We evaluated four ECOG extraction approaches on unstructured clinical notes from patients with non–small cell lung cancer, multiple myeloma, or ovarian cancer (2017-2021). The approaches were a rule-based natural language processing algorithm, simple LLM prompting, and two advanced prompts (chain-of-thought and Double Filtering) using a domain-tuned LLM (LLAMAv3.2). Performance was measured on a binary outcome (any ECOG documented v none) and a three-class outcome (ECOG 0-1 v ≥2 v none) and via an adapted QUEST questionnaire for human evaluation. RESULTS Both CoT and double filtering technique (DFT) achieved 94% accuracy, outperforming the rule-based method (91%) and simple prompting (86%). DFT had the highest specificity (0.91) and positive predictive value (PPV; 0.93), whereas CoT attained the highest sensitivity (0.98). In the QUEST evaluation, DFT and CoT scored higher on output quality, reasoning, bias reduction, and user satisfaction than the simple prompt. DFT received the top satisfaction rating. In the three-class analysis, DFT and CoT again performed best (accuracy 0.91 v 0.87) and DFT was most sensitive for ECOG ≥2 cases. Estimates for ECOG ≥2 remained imprecise because of the small sample (n = 20). All methods sometimes hallucinated ECOG status. CONCLUSION Advanced LLM prompting improved ECOG extraction over basic methods. DFT and CoT each showed specific strengths (DFT had higher PPV and user satisfaction; CoT achieved higher sensitivity). These approaches appear to be generalizable across cancer types. Key implementation considerations include computational cost and human oversight. Overall, advanced prompting can standardize ECOG documentation, accelerate patient cohort identification, and inform personalized treatment planning.

Durvalumab versus Physician’s Choice Chemotherapy in Recurrent Ovarian Clear Cell Adenocarcinoma (MOCCA/APGOT-OV2/GCGS-OV3): A Multicenter, Randomized, Phase 2 Trial

Abstract Purpose: The optimal treatment of recurrent ovarian clear cell carcinoma (rOCCC) remains unknown. This is the first randomized trial to compare durvalumab with chemotherapy in rOCCC. Patients and Methods: MOCCA is a randomized, phase 2 trial conducted in Singapore, Korea, and Australia. Eligible patients had rOCCC with recurrence after platinum-based chemotherapy, Eastern Cooperative Oncology Group performance status ≤2, and no prior immune checkpoint blockade. Patients were randomly assigned (2:1) to durvalumab (1,500 mg every 4 weeks) or chemotherapy. Patients progressing on chemotherapy were allowed to cross over to durvalumab. The primary outcome was progression-free survival. Secondary outcomes included overall survival, objective response rates, and safety. Results: Forty-eight eligible women were assigned to durvalumab (N = 31) or chemotherapy (N = 17). The median progression-free survival was 7.6 [95% confidence interval (CI), 7.0–16.0] and 14.0 (95% CI, 7.0–32.9) weeks with durvalumab and chemotherapy, respectively (HR = 1.6; 95% CI, 0.8–3.0; P = 0.92). The median overall survival was 37.9 (95% CI, 21.7–143.0) and 40.6 (95% CI, 25.0–not reached) weeks, respectively (HR = 1.5; 95% CI, 0.7–3.3; P = 0.85). The difference in objective response rates between the groups was not statistically significant (durvalumab 9.7% vs. physician’s choice chemotherapy 18.8%; difference −9.1%; 95% CI, −31.3% to 12.9%; P = 0.83). Fewer all-grade (35.5% vs. 68.8%) and high-grade (9.7% vs. 31.3%) treatment-related adverse events were observed for durvalumab. PD-L1 combined positive score (CPS)+ was observed in 28.9% (CPS ≥1%) and 10.5% (CPS ≥10%) of patients. PIK3CA mutations were associated with time to progression on durvalumab ≥12 weeks [relative risk (mutated vs. wild-type) 2.83; 95% CI, 1.16–14.17]. Conclusions: Durvalumab was well-tolerated but did not improve efficacy outcomes compared with chemotherapy in rOCCC.

Clearer Horizons: The latest advances in clear cell ovarian cancer treatment

This review aims to consolidate the current understanding of Clear Cell Ovarian Carcinoma (CCOC), a rare yet distinct subtype of epithelial ovarian cancer. CCOC exhibits unique epidemiological, clinical and molecular features, being one of the most frequent subtypes in East Asia, often diagnosed at an early stage and frequently affecting younger women. Its hallmark characteristics include high resistance to conventional chemotherapy, poor prognosis in advanced stage and a molecular profile distinct from high-grade serous histotype. Specifically, CCOC is characterized by a low prevalence of TP53 mutations, BRCA1/2 mutations and homologous-recombination deficiency, but a high frequency of ARID1A, along with other SWI/SNF alterations, and PIK3CA mutations, both of which represent promising therapeutic targets. Despite the absence of validated therapies for CCOC so far, significant advancements in preclinical research and emerging clinical strategies including immunotherapy combinations offer hope for improved outcomes. Given the rarity of this cancer type, collaborative research and global partnerships have enabled robust studies and the implementation of trials with innovative personalized therapeutic approaches. The objective of this report is to explore the epidemiology, clinical and molecular characteristics, current standard of care and evolving therapeutic strategies for CCOC patients. It will not only highlight the progress made so far, but most importantly identifies critical research priorities to optimizing patient outcomes.

Controversies in the management of clear cell carcinoma of the uterus and ovary

Clear cell ovarian and endometrial carcinomas are rare and aggressive gynecologic malignancies that present unique challenges owing to their underrepresentation in clinical trials and limited prospective data. In this report, we aimed to explore 3 major controversies in the management of clear cell ovarian and endometrial carcinomas, highlighting areas that require further investigation. First, we addressed the unique phenotypic characteristics of clear cell ovarian carcinoma and clear cell endometrial carcinoma and whether they should be considered a unified disease entity or a distinct disease. Recent trials grouped these carcinomas, potentially expanding their therapeutic options. However, emerging molecular data underscores the significant differences between clear cell ovarian carcinoma and clear cell endometrial carcinoma, raising questions regarding this combined approach. This distinction is critical in guiding tailored treatment strategies. Second, we examined the management of localized diseases. Although early-stage diagnoses are common in clear cell carcinomas, optimal surgical and adjuvant treatment strategies remain uncertain. Current practice often relies on data from broader studies with limited inclusion of clear cell histology. This review underscores the need for more specific evidence to refine treatment protocols and balance efficacy with the minimization of treatment-related morbidity. Third, we explored novel therapeutic strategies for the treatment of recurrent diseases. Advances in the understanding of the biology of clear cell carcinomas have identified potential targets in the immune microenvironment, cellular processes, and metabolism. Ongoing clinical trials are investigating these approaches, which hold promise in transforming the treatment landscape and outcomes. In conclusion, this review emphasizes the necessity for international collaboration and the inclusion of diverse patient populations to address the challenges posed by cell carcinomas. By focusing on these controversies, we aim to stimulate further research and support more evidence-based personalized approaches for the management of these rare but challenging cancers.

Current practices and challenges in genetic testing and counseling for women with breast and ovarian cancer in Asia

AbstractAimThis study assesses current practices and challenges in genetic testing and counseling (GT and C) for breast cancer gene (BRCA)1/2 mutations in Asia, considering the increased risk of ovarian cancer (OC) and breast cancer (BC) in women carrying these mutations.MethodsInsights were gathered through a questionnaire from breast surgeons, gynecologists, oncologists, and genetic clinicians in 10 Asian countries: Thailand, Hong Kong, South Korea, India, Vietnam, Malaysia, the Philippines, Taiwan, Singapore, and Indonesia. The questionnaire covered their knowledge, attitudes, and practices in GT and C for BRCA1/2 mutations, along with information on perceived gaps and unmet needs in the region.ResultsA total of 61 specialists participated in the survey. GT and C for BRCA1/2 mutations were less frequently offered in Asia compared to Western countries. Among the guidelines used, the National Comprehensive Cancer Network (NCCN) guidelines alone or in combination with other guidelines (American Society of Clinical Oncology [ASCO], National Institute for Health and Clinical Excellence [NICE], and European Society for Medical Oncology [ESMO]) were preferred for both BC and OC. Limited access to genetic counselors posed a significant challenge, resulting in delayed or no GT. Pretest genetic counseling was provided by the respondents themselves. Germline testing was preferred for BC, whereas both germline and somatic testing were preferred for OC, with the most preferred option being a multipanel germline test.ConclusionDisparities exist in GT and C practices between Asian and Western countries. To address this, steps, such as patient and doctor education, increased accessibility and affordability of GT and C services, and improved infrastructure for identifying gene mutations, should be taken.

Ovarian cancer

Epithelial ovarian cancer (EOC) describes a group of diseases characterized by differing pathogeneses, molecular profiles, histologies and prognoses. The low incidence of each distinct histological type of EOC poses challenges for obtaining an accurate diagnosis, robust evidence to guide management, and a mechanistic understanding to ensure availability of effective therapies. Most EOCs, including high-grade serous ovarian cancer, predominantly originate from the fimbriated ends of the fallopian tube, whereas low-grade serous, clear cell, endometrioid and mucinous EOCs are thought to originate from other tissues. Despite recognized genetic susceptibilities for the disease, no effective screening is available and late-stage diagnosis remains common. Known genetic susceptibilities are addressed by risk reduction surgery including removal of both fallopian tubes and both ovaries. Management is predominantly based on adequate surgery and chemotherapy with carboplatin and paclitaxel, with the addition of anti-angiogenic therapy as indicated. The incorporation of poly(ADP-ribose) polymerase inhibitors into first-line therapy has considerably altered outcomes in some women with EOC who have defective homologous recombination DNA repair, including in those with BRCA1 and/or BRCA2 mutations. Other molecular characteristics are important in distinct types of EOC, but the use of matched targeted therapies remains under investigation, as does the role of immunotherapy for EOC, for which trial data have been disappointing to date. Translationally enriched clinical trials will be important to further explore and validate accurate biomarkers to better guide clinical care.

How long is long enough? An international survey exploring practice variations on the recommended duration of maintenance therapy with PARP inhibitors in patients with platinum sensitive recurrent ovarian cancer and long-term outcomes

There are no data, and thus no consensus, on the optimal duration of poly(ADP-ribose) polymerase (PARP) inhibitor maintenance therapy for exceptional responders (here defined as progression-free for 5 years or longer) with platinum sensitive recurrent ovarian cancer. The current licence is to continue PARP inhibitors until progression or toxicity; however, international practice varies considerably. The risks of late progression and late-onset myeloid malignancies, defined as occurring beyond 5 years of PARP inhibition, are unknown. This study aims to examine the practice patterns and opinions regarding the management and surveillance protocols of exceptional responders with platinum sensitive recurrent ovarian cancer. An online international survey of experts from June 2023 to June 2024 was carried out, disseminated at Gynaecologic Cancer Intergroup meetings and by Chairs of Cooperative Groups. 210 responses were received from 26 countries including Australia (27 respondents), Germany (24), the UK (21), the Netherlands (16), France (13), Spain (12), Canada (12), Italy (11), Japan (11), and other countries (63). Most respondents did not have institutional or trials group guidelines regarding duration of PARP inhibitors (154, 73.3%). For the minority with guidelines, recommendations varied: 1 year (2), 2 years (13), 3 years (4), and indefinite treatment (22). Individual practice varied considerably for those without guidelines: most (116, 76.3%) recommended ≥5 years of PARP inhibition, of which 73 (48.0%) recommended indefinite PARP inhibition. Sixty-six respondents (31.4%) reported having patients with late progression and 46 (22.0%) had cases with late-onset myeloid malignancies. Surveillance practices varied widely across all respondents. This international survey highlights the diverse practice variations and disparate views on the optimal duration of maintenance therapy with PARP inhibitors in platinum sensitive recurrent ovarian cancer. The responses suggest a notable risk of late progression and myelodysplastic syndrome/acute myeloid leukemia among exceptional responders which needs confirmation. Detailed individual patient data is required to draw more reliable conclusions; another study is underway addressing this.

Quantitative imaging of RAD51 expression as a marker of platinum resistance in ovarian cancer

Early relapse after platinum chemotherapy in epithelial ovarian cancer (EOC) portends poor survival. A-priori identification of platinum resistance is therefore crucial to improve on standard first-line carboplatin-paclitaxel treatment. The DNA repair pathway homologous recombination (HR) repairs platinum-induced damage, and the HR recombinase RAD51 is overexpressed in cancer. We therefore designed a REMARK-compliant study of pre-treatment RAD51 expression in EOC, using fluorescent quantitative immunohistochemistry (qIHC) to overcome challenges in quantitation of protein expression in situ. In a discovery cohort (n = 284), RAD51-High tumours had shorter progression-free and overall survival compared to RAD51-Low cases in univariate and multivariate analyses. The association of RAD51 with relapse/survival was validated in a carboplatin monotherapy SCOTROC4 clinical trial cohort (n = 264) and was predominantly noted in HR-proficient cancers (Myriad HRDscore < 42). Interestingly, overexpression of RAD51 modified expression of immune-regulatory pathways in vitro, while RAD51-High tumours showed exclusion of cytotoxic T cells in situ. Our findings highlight RAD51 expression as a determinant of platinum resistance and suggest possible roles for therapy to overcome immune exclusion in RAD51-High EOC. The qIHC approach is generalizable to other proteins with a continuum instead of discrete/bimodal expression.

A phase 1b, multicentre, dose escalation, safety and pharmacokinetics study of tilvestamab (BGB149) in relapsed, platinum-resistant, high-grade serous ovarian cancer (PROC) patients

Abstract Background Tilvestamab is a highly selective humanised immunoglobulin G1 anti-AXL monoclonal antibody. This phase 1 study evaluated its optimal dose, safety, tolerability, immunogenicity and pharmacokinetics (PK) in relapsed platinum-resistant HGSOC patients. Methods Patients received tilvestamab in three dose levels (1 mg/kg, 3 mg/kg and 5 mg/kg) via IV infusion every 2 weeks. Primary objectives included safety, tolerability and PK. Exploratory objectives included overall response, progression-free survival (PFS) and quality-of-life measures. Pharmacodynamic included AXL expression, gene and protein changes by transcriptomic and proteomic analysis. Results Between 25 February 2021 and 4 February 2022, 16 patients were enroled across 8 sites in Singapore, Korea, United Kingdom, and Norway. Median treatment duration was 6.1 weeks. Grade 3 or higher treatment-emergent adverse events occurred in 62.5% patients, but none were tilvestamab-related. Common events included fatigue (38%), anorexia (38%) infections (31%), anaemia (25%) and dyspnoea (25%). No objective responses were observed, but 7 (44%) had stable disease at 6 weeks. PK showed dose-proportional exposure and steady-state by the second dose. Pharmacodynamic analyses revealed reduced fibrosis-related gene signatures and AXL protein expression. Epithelial-mesenchymal transition reversal was seen in 2 patients. Conclusion Tilvestamab was well-tolerated and further studies to examine the efficacy of AXL inhibition in other indications are required. Clinical trial registration This trial is registered at https://clinicaltrials.gov. Registration number: NCT04893551. EudraCT Number: 2020-001382-36

Comprehensive characterization of genomic features and clinical outcomes following targeted therapy and secondary cytoreductive surgery in OCCC: a single center experience

Ovarian clear cell carcinoma (OCCC) is associated with chemoresistance. Limited data exists regarding the efficacy of targeted therapies such as immune checkpoint inhibitors (ICI) and bevacizumab, and the role of secondary cytoreductive surgery (SCS). We retrospectively analyzed genomic features and treatment outcomes of 172 OCCC patients treated at our institution from January 2000 to May 2022. Next-generation sequencing (NGS) was performed where sufficient archival tissue was available. 64.0% of patients were diagnosed at an early stage, and 36.0% at an advanced stage. Patients with advanced/relapsed OCCC who received platinum-based chemotherapy plus bevacizumab followed by maintenance bevacizumab had a median first-line progression-free survival (PFS) of 12.2 months, compared with 9.3 months for chemotherapy alone (hazard ratio=0.69; 95% confidence interval [CI]=0.33, 1.45). In 27 patients who received an ICI, the overall response rate was 18.5% and median duration of response was 7.4 months (95% CI=6.5, 8.3). In 17 carefully selected patients with fewer than 3 sites of relapse, median PFS was 35 months (95% CI=0, 73.5) and median overall survival was 96.8 months (95% CI=44.6, 149.0) after SCS. NGS on 58 tumors revealed common mutations in Our study demonstrates encouraging outcomes with bevacizumab and ICI, and SCS in select relapsed OCCC patients. Prospective trials are warranted.

109Works
15Papers
75Collaborators
2Trials
Ovarian NeoplasmsBiomarkers, TumorCarcinoma, Ovarian EpithelialAdenocarcinoma, Clear CellNeoplasmsEndometrial Neoplasms

Positions

2013–

Associate Professor

National University of Singapore · Dept of Medicine, Yong Loo Lin School of Medicine

2013–

Principal Investigator

National University of Singapore · Cancer Science Institute

2013–

Senior Consultant

National University Cancer Institute · Medical Oncology

2012–

Fellow

Princess Margaret Cancer Centre · Gynecologic Medical Oncology and Drug Development

2008–

Registrar

Royal Marsden Hospital · Medical Oncology

2005–

Cancer Research UK PhD Fellowship

The Institute of Cancer Research

Country

SG